1. Technical Field of the Invention
The present invention relates to a liquid crystal device and a manufacturing method therefor, and more specifically, it relates to a structure of a vertical conducting portion formed between two substrates making up the liquid crystal device.
2. Description of the Related Art
In general, a conventional liquid crystal is formed by: forming electrodes and wires connected to the electrodes on two substrates, respectively; further forming alignment layers thereon; attaching the two substrates to each other via a sealing member and curing the sealing member, the substrates being compression-bonded so as to provide a desired gap between the substrates, thereby fixing the gap between the substrates; and injecting a liquid crystal inside the sealing member and sealing it.
In such a liquid crystal device, normally, one substrate is provided with a projecting portion that projects outward beyond an outer edge of the other substrate, and the wire connected to the electrode formed on a substrate surface is drawn out onto a surface of the projecting portion, a distal end portion of the wire being formed as an external terminal. At this time, there are cases where the projecting portions are formed on the two substrates, respectively, and the wires connected to the electrodes formed on the respective substrate surfaces are drawn out onto the surfaces of the respective projecting portions. In many cases, however, the projecting portion is formed only on one of the two substrates. And in this case, a vertical conducting portion for conductively connecting the electrode on the substrate, in which the projecting portion is not formed, to the external terminal on the projecting portion formed on the other substrate is provided. In the vertical conducting portion, there are some cases where a part of a sealing member for sealing a liquid crystal in between two substrates attached to each other is formed into a conductive area.
FIG. 5 and FIG. 6 are a schematic sectional view and a schematic top plan view of a vertical conducting portion in the above liquid crystal display panel. A conducting region 130a that has been cured in a compression-bonded state is disposed between two transparent substrates 110 and 120 making up the liquid crystal display panel. The conducting region 130a is a part of the sealing member. In the conducting region 130a, spacers 131 composed of resin balls, glass fibers, glass balls, or the like for restricting a cell thickness of the liquid crystal display panel and the foregoing conductive particles 133 are scatteringly disposed, as shown in FIG. 6. A plurality of external wires 111b which are formed to be drawn onto the surface of a projecting portion 110a of the transparent substrate 110 and are formed of a transparent conductive member are formed in parallel on a surface of the transparent substrate 110 that is in contact with the conducting region 130a. Inner end portions 111c of the external wires 111b are in contact with the conducting region 130a of the sealing member. Internal wires 121b which are connected to electrodes, which are not shown, and extend toward an outer edge of the substrate are formed on a surface of the transparent substrate 120. Outer end portions 121c of the internal wires 121b are in contact with the conducting region 130a. The conductive particles 133 in the conducting region 130a are in conductive contact with both the inner end portions 111c and the outer end portions 121c. Hence, the electrodes, not shown, which are formed on the surface of the transparent substrate 120 are conductively connected to the external wires 111b formed on the surface of the projecting portion 110a through the internal wires 121b and the conductive particles 133.
The conventional liquid crystal display panel has been configured such that the outer edges of the alignment layers 113 and 123 are disposed farther inward than the area where the sealing member or the foregoing conducting region 130a is disposed in order to prevent the alignment layers 113 and 123 from interfering with conductive contact between the inner end portions 111c of the external wires 111b and the outer end portions 121c of the internal wires 121b, and the conductive particles 133.
In recent years, however, with an increasing demand for liquid crystal display panels to provide larger display areas and reduced sizes, there has been increasing necessity for making the portions surrounding the display areas (the areas where the electrodes are arranged and formed on substrate surfaces) as narrow as possible in designing a liquid crystal display panel (thereby narrowing the frames of the liquid crystal display panels). To narrow the peripheral portion of a display area, the space between an outer edge of the display area and an inner edges of the vertical conducting portion must be also reduced. As a method for applying the alignment layers 113 and 123, a cheap printing method, such as flexo printing or offset printing that exhibits lower patterning accuracy than photolithography, which is a patterning method for transparent electrodes, etc. is used. Therefore, in order to securely position the outer edges of the alignment layers 113 and 123 between the outer edge of the display area and the inner edge of the vertical conducting portion, it is required to design the space between the outer edge of the display area and the inner edge of the vertical conducting portion with accuracy as good as or better than the printing accuracy of the alignment layers. For this reason, a conventional manufacturing process has been having some limitation, which is attributable to patterning accuracy of the alignment layers, in achieving a narrower area surrounding the display area without adopting a method that leads to higher cost, such as changing a method for applying the alignment layers.
Accordingly, the present invention has been made with a view toward solving the above problem, and the object of the present invention is to provide a structure that enhances freedom of designing and allow a larger display area and a reduced size of a liquid crystal device, by adopting a structure of a vertical conducting portion that is capable of achieving a narrower portion surrounding the display area, without being affected by a patterning accuracy of the alignment layers.
To solve the problem described above, a liquid crystal device in accordance with the present invention is formed by a first substrate and a second substrate which have electrodes and alignment layers formed on surfaces thereof and are attached to each other with a liquid crystal sealed in therebetween, comprising: a first conductive member formed on a surface of a peripheral portion of the first substrate; a second conductive member formed on a portion on the second substrate that opposes the first conductive member; and a vertical conducting portion having a conductive material containing conductive particles for electrically conductive connection between the first conductive member and the second conductive member, wherein the alignment layer is formed such that it extends to cover the surface of at least one of the first conductive member and the second conductive member, and the conductive particles break through the alignment layer to be in conductive contact with the first conductive member and the second conductive member.
According to the present invention, since the conductive particles in the conductive member break through the alignment layers to contact the first conductive member and the second conductive member, it is no longer necessary to avoid the vertical conducting portion in forming the alignment layers as in the prior art, eliminating the restrictions on the positions of the outer edges of the alignment layers. As a result, design freedom in the peripheral portion of the display area of a liquid crystal device is enhanced, so that the peripheral portion can be made narrower, thus permitting a larger display area and a reduced size of the liquid crystal device to be achieved. Furthermore, since the conductive members, such as wires, in the vertical conducting portion can be covered by the alignment layers, the corrosion resistance of the vertical conducting portion can be improved. Moreover, the alignment layers can be formed in a larger area, making it possible to enhance uniformity of a rubbing condition.
In the present invention described above, the alignment layer may cover at least one of the first conductive member and the second conductive member, and the conductive particles break through the alignment layer covering one of the conductive members to be in conductive contact with the conductive member and also in conductive contact with the other conductive member. The alignment layer may only partially cover the first conductive member or the second conductive member rather than covering it entirely. It is, however, more desirable and effective that the respective alignment layers cover the first conductive member and the second conductive member, and the conductive particles break through both alignment layers to be in conductive contact with both the first conductive member and the second conductive member.
In the present invention, the alignment layer that covers at least one of the first conductive member and the second conductive member is preferably formed on an entire surface of an area of a substrate surface where the first substrate and the second substrate oppose each other, except a place where the conductive particles are disposed. According to the present invention, since the alignment layer is formed on the entire surface in the area where the substrates oppose each other except the place where the conductive particles are disposed, the alignment layer can be formed more easily, and the uniformity of the rubbing condition can be further improved.
In the present invention, the conductive member is preferably a sealing member for sealing a liquid crystal in between the first substrate and the second substrate.
Furthermore, the liquid crystal device according to the present invention includes a first substrate and a second substrate which have electrodes and alignment layers formed on surfaces thereof and are attached to each other with a liquid crystal sealed in therebetween, comprising: a first conductive member that is formed on a surface of a peripheral portion of the first substrate and electrically connected to the electrode; a second conductive member that is formed on a portion on the second substrate opposing the first conductive member and electrically connected to the electrode; and a vertical conducting portion having a conductive material containing conductive particles for conductive connection between the first conductive member and the second conductive member, wherein the alignment layer is provided on a surface of at least one of the first conductive member and the second conductive member except a place where the conductive particles are provided, and the conductive particles are in conductive contact with the first conductive member and the second conductive member.
Next, a manufacturing method according to the present invention is a manufacturing method for a liquid crystal device having a first substrate and a second substrate which have electrodes and alignment layers formed on surfaces thereof and are attached to each other with a liquid crystal sealed in therebetween, and comprising a first conductive member formed on a surface of a peripheral portion of the first substrate, a second conductive member formed on a portion on the second substrate that opposes the first conductive member, and a vertical conducting portions having a conductive material containing conductive particles for conductive connection between the first conductive member and the second conductive member, whereby the alignment layer is extendedly formed to cover the surface of at least one of the first conductive member and the second conductive member, and the first substrate and the second substrate are attached to each other via the conductive material and compression-bonded thereby to cause the conductive particles break through the alignment layer to be in conductive contact with the first conductive member and the second conductive member.
In the present invention, preferably, in a step for extendedly forming the alignment layer to cover at least one of the first conductive member and the second conductive member, the alignment layer is formed on an entire area of the substrate surface where the first substrate and the second substrate oppose each other. In this case, the alignment layers are preferably formed over the entire substrate surfaces of both the first substrate and the second substrate, and after completing a panel structure, the alignment layers on the area where the external terminals are arranged are removed.
In the present invention, the conductive material is preferably used as a sealing material for sealing a liquid crystal in between the first substrate and the second substrate.
In the individual aspects of the present invention described above, it is further preferable that a thickness of the alignment layers ranges from 100 to 400 angstroms, and more preferably, from 100 to 300 angstroms.
In the individual aspects of the present invention described above, an outside diameter of the conductive particle is preferably 5 to 20% larger than a cell thickness.